Why can't I use "GeForce 9500 GT" for GPU rendering with Cycles?
The NVIDIA GeForce 9500 GT is from the GeForce 9 series, which doesn't fulfill the minimum requirements for Blender 2.8x.


  Supported Graphics Cards
  
  
  NVIDIA: GeForce 400 and newer, Quadro Tesla GPU architecture and newer, with NVIDIA drivers (list of all GeForce and Quadro
  GPUs)
  





  CUDA
  
  CUDA requires graphics cards with compute capability 3.0 and higher.
  To make sure your GPU is supported, see the list of Nvidia graphics
  cards with the compute capabilities and supported graphics cards.
  CUDA GPU rendering is supported on Windows, macOS, and Linux.


It's therefore neither supported for GPU rendering, which requires CUDA compute capability 3.0, nor for running Blender in general. The latter may still work, however given that old hardware doesn't receive driver updates anymore, you may be experiencing graphics glitches or crashes. The latest driver available for the GeForce 9 series is from 2016.